HV insulation components work in a very harsh environment. These elements, depending on their application, are exposed to high voltage and high temperature (>100C), outdoor work, dielectric gases, and many other conditions. For many years such elements have been produced mainly from thermoset materials with filler, in particular epoxy resin. In general, the current material and its processing lead to a labor-intensive and complex manufacturing process. Additionally, epoxy material is very problematic to recycle thus, it would be desirable to find a material which is easier to process and more ecofriendly. Nowadays, we see more and better polymers like thermoplastics that seem to be good alternative. But their implementation is not an easy task and requires performing a lot of tests which are very challenging. The paper consists of selected HV insulation requirements and examples of tests that must be performed to find the best material candidates. Performed analyses and tests for different thermoplastic materials show its potential for implementation as alternative to epoxy resin. This way seems to be the right one as thermoplastic material offer a lot of benefits especially in terms of sustainability and circular economy.

Reliability and security of power systems, especially in areas prone to earthquakes, depends on the seismic withstand of its components and interaction of these components with other elements. All relevant power products and components should be designed and tested to guarantee high seismic performance. Option which is strongly recommended for seismic qualification is shake table test. This way is very expensive and in some cases like power transformers impossible due to its weight and size. Because of this the numerical analyses can be very helpful to determine the dynamic characteristic of the system. This way is more and more used during evaluation of seismic performance of power products, especially in the design phase. In the paper a different numerical approaches for seismic analyses of the power transformers have been presented. In the first part of the article focus was put on typical simulation methods defined by IEEE and IEC standards. This approach is dedicated only for transformer’s components. Due to fact that standards do not provide clear information about fluid influence on power equipment during seismic events, some investigations related with oil filled transformers were done and summarized. Three different numerical methods were investigated. First one is built based on the Fluid-Structure Interaction (FSI) methodology. In this approach combination of different software (CFD, structural, and coupling code) is used to cover phonemes related with fluid dynamics and structural analyses. FSI methodology gives a wide possibility but, it’s very complex however, is very complex which can be a disadvantage for very complex objects. Next one uses acoustic elements, where the fluid is modeled as acoustic medium. This is method which allows to take into account fluid during seismic simulations in simplified way. The last one uses Lagrange and Euler element formulations (CEL) in which sloshing effect of the oil in power products can be considered. All this approaches can be very helpful to determine the dynamic characteristic of the transformers and its equipment including fluid.

Acoustic radiation efficiency is a parameter which characterizes the sound radiation effectiveness of a vibrating surface. It can be useful in describing the coupling between a vibrating element and the origin of its structure-borne noise. This paper discusses the possibilities of using acoustic radiation efficiency parameter as an indicator applied to assess the noise emitted by power machinery. Acoustic methods, including intensity scanning, Laser Doppler Vibrometry (LDV) and numerical analyses, were used to determine the vibration velocity and, subsequently, calculate and evaluate the radiation efficiency values. Results of measurements and FEM simulations are presented along with comparison of the methods.

Recently, an increasing need for unusual and more demanding tasks to be performed by robots in automotive, aerospace, food, and beverage industries can be observed. At the same time, compactness is an essential factor influencing the design of modern robot controllers, whereas the size and weight reduction makes thermal management in electric devices much more required than in the past device generations. In this article, an analytical, numerical, and experimental approach to optimization of thermal management in an ABB IRC5 robot controller is presented. Both the fundamentals of the developed approach and the results of investigations are discussed including indications regarding the design improvement.

The epoxy resin-based systems with silica filler are widely used in many products like medium and high voltage electrical components due to its very good dielectric and mechanical properties. Such products require to operate in harsh environments which may activate the process of formation and propagation of the cracks within the resin material. The cracking phenomenon contributes also to manufacturing problems. The epoxy based parts are very often produced by casting during which (post) curing cracking may appear.In order to better understand the cracking phenomena of epoxy resin there is a need to investigate microstructural damage. The work presented in this paper includes both experimental and numerical analysis of microstructure crack initiation and propagation in silica filled epoxy. Basic information about epoxy resin-based systems and its applications are presented. Next, basics of the fracture mechanics with description of available numerical approaches are described. The numerical simulations were prepared for Representative Volume Element (RVE) which was obtained using home-made tool for image digitalization. Experimental analysis consist of in-situ tensile tests and microstructural observations with Scanning Electron Microscope (SEM). At the end a summary with conclusions related with prepared numerical analysis and experiments is included. The presented research of the damage of silica/epoxy composite confirms that analysis of the epoxy resin microstructural damage is not trivial and further study is required for its better understanding. Copyright (C) 2016 The Authors. Published by Elsevier B.V.

Design considerations related to noise pollution have become extremely important recently in many industries. Despite the wide range of applications and various noise spectrum the methodology remains quite common. The power products operating in the power systems are very often affected by a noise emission side effect and must be carefully designed with respect to the resulting noise emission and its influence on the surrounding environment consequently. Noise management, design concept examples as well as the modern techniques for noise sources characterization in transformers are presented in this paper.

This paper provides examples of application of advanced numerical modelling to analysis of transformer operation and design optimization. Computer simulations are useful tools that help engineers in keeping the balance between the continuous pursuit of reducing the cost of transformers and assuring high quality performance. The presented examples refer to different types of transformers and different problems in their operation. They include analysis of thermal shock test of the dry transformer, analytical, experimental and numerical modeling for improvement of passive cooling in oil-immersed distribution transformers and seismic analyses of power transformers. In each case the numerical modelling approach is presented and the example results are shown. Simulations of thermal shock test indicate large temperature gradients that may have essential influence on mechanical behavior of the dry transformer coil. Further, the higher cooling efficiency of the new concept of passive cooling is validated using mathematical, numerical and experimental models. Finally, the proposed numerical methods of seismic analysis indicates that oil has an influence on structure dynamics and the whole transformer system must be taken into account during vibration analysis.

This paper describes a unique multiphysics simulation tool allowing one to analyze and optimize reactive molding process used for the production of electrical insulation (in the form of epoxy resin embedding) in many power products. The presented methodology differs from the standard approach, since it excludes the requirement for high end-user’s knowledge and experience in the area of CFD (Computational Fluid Dynamics) and mechanical simulations. The role of the tool user is limited only to the definition of CAD geometry and process parameters via user-friendly Website. The remaining operations involved in numerical computations, including CAD geometry analysis and discretization, solving and postprocessing, are executed automatically and the simulation results are published online. In this way the presented tool gives engineers an opportunity to verify the product/mold design and manufacturing process prior to the production launching or to improve the existing solutions without time-consuming and expensive experimental trials. In addition, the time needed to perform simulation (especially to prepare numerical mesh) is significantly shortened.